The development of solid block cleaning compositions has revolutionized the manner in which detergent compositions are dispensed by commercial and institutional entities that routinely use large quantities of cleaning materials. Solid block compositions offer unique advantages over the conventional liquids, granules or pellet forms of detergents, including improved handling, enhanced safety, elimination of component segregation during transportation and storage, and increased concentrations of active components within the composition. Because of these benefits, solid block cleaning compositions, such as those disclosed in U.S. Pat. Nos. RE 32,763, RE 32,818, 4,680,134 and 4,595,520, have quickly replaced the conventional composition forms in commercial and institutional markets.
Various hardening mechanisms have been used in cleaning and sanitizing compositions for converting a fluid composition to a solid mass for containment and modification of the solubility of the active ingredients during use. For example, the active ingredients may be combined with the hardening agent under melting temperatures, commonly referred to as a "molten process," to achieve a homogeneous mixture, and the melt then poured into a mold and cooled to a solid form. Solid alkaline detergent compositions may also be prepared from an aqueous emulsion of detergent ingredients combined with a solidifying agent that can hydrate to bind free water in the emulsion which, optionally after heating and cooling, hardens to a solid.
U.S. Pat. No. 5,019,346 to Richter, for example, discloses a solid block drain treatment product formed by heating a mixture containing a chemical sanitizer and a hardening agent such as urea or an alkyl amide such as stearic monoethanolamide or stearic diethanolamide, and decanting the melt into containers. U.S. Pat. No. 4,861,518 to Morganson discloses a solid cleaning concentrate formed by heating an anionic or nonionic surfactant system with a hardening agent such as polyethylene glycol, at about 130-150.degree. F. to form a melt. The melt is combined with other ingredients including a solubilizer and an alkali, to form a homogeneous mixture, and the molten mixture then poured into a capsule container to cure or harden. U.S. Pat. Nos. 4,595,520 and 4,680,134 to Heile et al. disclose a solid alkaline detergent formed from an aqueous emulsion containing a sodium condensed phosphate hardness sequestering agent and an alkaline builder salt such as sodium hydroxide, which is solidified by incorporating a hydratable hardening agent such as an anhydrous sodium carbonate and/or sodium sulfate. Preferably, the emulsion is heated to form a molten mass, and then cooled to effect solidification. U.S. Pat. No. 5,064,554 to Jacobs et al. discloses a solid detergent in the form of a fused block manufactured by preparing a melt of alkali metal silicate, alkali metal hydroxide, optionally water, an active chlorine donor and/or an organic complexing agent, combining the melt with a penta-alkali metal triphosphate, introducing the melt into a flow mixer, and pouring the molten mixture into a mold to solidify.
Solid block cleaning and sanitizing compositions and rinse aids provide a significant improvement over the conventional liquid, granular and pelletized cleaning compositions. Although the molten process is useful for preparing solid block compositions, time and expense would be saved if heating and cooling of the composition could be minimized or eliminated from the process, and higher viscosities could be used. Also, lower process temperatures would better facilitate the use of heat-sensitive ingredients in cleaning compositions. In addition, less sturdy packaging would be required if the processed mixture could be dispensed at a lower temperature. Furthermore, eliminating molten temperatures would avoid swelling and deformation of the solid product.
Various attempts have been made to manufacture cleaning compositions by an extrusion process. U.S. Pat. No. 5,061,392 to Bruegge et al., for example, discloses a method of forming a detergent composition having a paste-like consistency, by combining a first aqueous solution containing a potassium tripolyphosphate and a second aqueous solution containing a water-soluble, sodium-based detergent builder, namely sodium hydroxide. Upon mixing, the viscosity of the mixture rapidly increases to form a highly viscous paste. In another extrusion method, as disclosed in U.S. Pat. No. 4,933,100 to Ramachandran, an organic detergent of particulate or patty form is formed by kneading together a synthetic organic detergent, a hydratable builder salt such as sodium tripolyphosphate, and water. The mixture is passed through an extruder and forced through openings at or slightly above room temperature and a low pressure to form a rod-shaped extrudate. A disadvantage of these processes is that a caustic, hydratable alkaline source is required to facilitate hardening of the processed composition after extrusion.
Therefore, an object of the invention is to provide a process for manufacturing a solid, non-caustic cleaning composition at a process temperature below the melt temperature of the ingredients. Another object is to provide a process for making a cleaning composition at low processing temperatures and high viscosities to achieve more rapid solidification of the cast or extruded composition. A further object is to provide a process that will substantially eliminate swelling of the solid cast or extruded composition and product. Yet another object is to provide a method for making a cleaning composition that includes a hardening agent, whereby the proportion of hardening agent in the composition is substantially reduced, and the amount of active ingredients is substantially increased, relative to the corresponding cleaning composition made by other processing techniques known and used in the art.